Initializing Communication for Multiple Transceivers

ABSTRACT

Methods, systems, and computer readable medium for initializing communication for multiple transceivers. In one aspect, a method includes launching an initialization process of a first transceiver. The initialization process includes obtaining, for a second transceiver, a set of handshake information and inserting the set of handshake information of the second transceiver into one or more registers that are transmitted with first handshake information of the first transceiver during initialization of the first transceiver. The initialization process includes initiating a communications channel for the second transceiver over the same physical communications medium using the set of handshake information that was inserted into the one or more registers, including transmitting, by the first transceiver, the first handshake information of the first transceiver together with the set of handshake information for the second transceiver over the same physical communications medium using the given set of tones.

BACKGROUND

This specification relates to initializing communication for multipletransceivers.

The modern high speed communication transceiver such as G.fast and G.hncan operate using various physical mediums such as twisted-pair phonewire or coaxial cable. However, before multiple devices commence normalcommunication between each other, the devices complete a handshakingprocess, G.handshake. The handshaking process is a negotiation ofacceptable communication parameters for each of the devices. The endresult of the handshaking process is an established communicationchannel between the devices.

SUMMARY

In general, one innovative aspect of the subject matter described inthis specification can be embodied in methods for initializingcommunication for multiple transceivers. One examplecomputer-implemented method includes the actions of launching aninitialization process of a first transceiver, where the initializationprocess uses a given set of tones to perform the initialization process.The initialization process includes obtaining, for a second transceiverthat is connected to a same physical communications medium as the firsttransceiver and uses the given set of tones to perform theinitialization process, a set of handshake information transferred bythe second transceiver during the initialization process. Theinitialization process includes inserting the set of handshakeinformation of the second transceiver into one or more registers thatare transmitted with first handshake information of the firsttransceiver during initialization of the first transceiver. Theinitialization process includes initiating a communications channel forthe second transceiver over the same physical communications mediumusing the set of handshake information that was inserted into the one ormore registers, including transmitting, by the first transceiver, thefirst handshake information of the first transceiver together with theset of handshake information for the second transceiver over the samephysical communications medium using the given set of tones.

Other embodiments of these aspects included corresponding systems andapparatus.

These and other embodiments can each, optionally, include one or more ofthe following features. In some aspects initiating a communicationschannel for the second transceiver over the same physical communicationsmedium can include receiving a reply to the first handshake informationthat includes a different set of handshake information for the secondtransceiver. The different set of handshake information can be includedin the one or more registers that are transmitted with the firsthandshake information used to initialize the first transceiver.Initiating a communications channel can include determining proposedcommunication parameters that the second transceiver will use tocommunicate with a remote transceiver over the communications channelestablished for the second transceiver based on the set of handshakeinformation and the different set of handshake information. The firsttransceiver can transmit the proposed communication parameters for thesecond transceiver.

In some aspects initiating the communications channel for the secondtransceiver can include receiving, by the first transceiver, anacceptance of the proposed communication parameters. In addition,initiating the communications channel for the second transceiver caninclude initiating independent communication between the secondtransceiver and a respective transceiver within the remote transceiver.

In some aspects, obtaining a set of handshake information transferredduring the initialization process, can include requesting, by the firsttransceiver and from the second transceiver, the set of handshakeinformation of the second transceiver, wherein the request includes atime period specifying an amount of time for the second transceiver totransmit the set of handshake information.

In some aspects, obtaining a set of handshake information transferredduring the initialization process can also include requesting, inparallel with the request from the second transceiver and from a thirdtransceiver, a second different set of handshake information of thethird transceiver.

In some aspects handshake information can include parameters forestablishing data transfer protocols between two or more transceivers.

Some devices include multiple transceivers and communicate with otherdevices that also have multiple transceivers. The devices with multipletransceivers can communicate with each other using one transmissionmedium. For example, when using one transmission medium, low-frequencytransceivers use the transmission medium's lower frequency band tocommunicate as opposed to high-frequency transceivers that use thetransmission medium's higher frequency band. Due to reliabilityconstraints that develop because of crosstalk, the handshaking processuses lower frequency signals passed through the lower part of thefrequency band. However, this makes higher frequency transceivers needto use the lower frequency band dedicated to the lower frequencytransceiver to execute the handshaking process. This either leaves thehigher frequency transceiver without a frequency band to use during thehandshaking process or requires the lower frequency transceiver tovacate the lower frequency band so the higher frequency transceiver cancomplete the handshaking process with another transceiver. Completingindividual handshaking processes for each of the multiple transceiverscan require more time than systems that implement the features describedbelow.

Particular embodiments of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. Techniques described herein allow for multipletransceivers to simultaneously execute the handshaking process using asingle set of handshake tones. For example, the handshake informationused to initialize a particular transceiver can be inserted into (e.g.,nested with) the initialization information that is used to initialize adifferent transceiver, thereby enabling the initialization informationfor both transceivers to be sent over the same set of tones at the sametime. By nesting handshake information for multiple transceivers, onetransceiver transmits the initialization information for multipledifferent transceivers over the same set of tones, thereby enablingmultiple different transceivers to be initialized without interferingwith the operation of other transceivers that share the same physicalcommunications medium. Enabling a single transceiver to simultaneouslytransmit initialization information for multiple different transceiversover the same communications medium enables multiple transceivers thatoperate within different frequency bands to be initialized at the sametime, thereby reducing interference and/or communications errors thatwould be injected into the system if the transceivers attempted toseparately perform their own respective initialization processes.

While some aspects of this disclosure generally describecomputer-implemented software embodied on tangible media that processesand transforms data, some or all of the aspects may becomputer-implemented methods or further included in respective systemsor devices for performing the described functionality. The details ofone or more embodiments of the subject matter described in thisspecification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a block diagram illustrating an example environment in whichtwo frequency division systems communicate over a same physicalcommunications medium.

FIG. 1B is a block diagram illustrating simultaneous transmission ofhandshake information for multiple transceivers.

FIG. 2 is a block diagram depicting a handshake message frame structure.

FIG. 3 is a flow chart of an example process for simultaneouslytransmitting handshaking information for multiple transceivers.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

The present disclosure describes methods, systems, and apparatus forsimultaneously initializing communication for multiple transceivers, forexample, by using one transceiver to transmit and/or receive theinitialization information for multiple transceivers. One portion of theinitialization process is the handshake process. The handshake processis used to establish a communication channel between two or moretransceivers. As described in detail throughout this document, duringthe handshake process a single transceiver transmits handshakeinformation for multiple transceivers over a same physical communicationmedium. In addition, the single transceiver uses a single tone set toconduct the handshake process for multiple transceivers, such that thehandshake information for multiple different transceivers aretransmitted over that single tone set at the same time. Thus, eachtransceiver can establish a communication channel between a respectiveone or more transceivers at the same time as the single transceiver.

In operation, a particular transceiver that is launching aninitialization process can receive a set of handshake information forone or more other transceivers. The particular transceiver embeds thereceived set of handshake information in shadow registers of aG.handshake (G.hs) message generated by the first transceiver toinitiate the handshake process. Thus, the particular transceivermodifies the G.handshake message to include not only the particulartransceiver's handshake information, but also the set of handshakeinformation for the one or more other transceivers.

The particular transceiver sends the modified G.handshake message to acorresponding transceiver (e.g., a transceiver with which the particulartransceiver is establishing a communications channel) over a single setof tones, e.g., using a low-frequency carrier signal. In someimplementations, the particular transceiver may transmit the modifiedG.handshake message over a low-frequency band that is dedicated totransferring handshake information during the handshake process (e.g.,as specified by G.994.1). As described in more detail below, thecorresponding transceiver to which the particular transceiver sends themodified G.handshake message (or another type of modified handshakemessage), can extract, from the modified G.handshake message, the set ofhandshake information for the one or more other transceivers, and passthat extracted handshake information to one or more correspondingtransceivers with which the one or more other transceivers areestablishing a communications channel. Meanwhile, the correspondingtransceiver that receives the G.handshake information can use thehandshake information from the particular transceiver to generate ahandshake reply.

The corresponding transceiver can also receive a set of other handshakereplies from the one or more other corresponding transceivers, and embedthe set of other handshake replies into the handshake reply beinggenerated by the corresponding transceiver. For example, the set ofother handshake replies can be inserted into shadow registers of thehandshake reply, in a manner similar to that by which the set ofhandshake information was embedded into the G.handshake message, tocreate a modified handshake reply. This modified handshake reply, whichincludes handshake reply information for multiple differenttransceivers, is then transmitted back to the particular transceiver toadvance the handshake process for each of the multiple differenttransceivers. Further transmissions between the particular transceiverand the corresponding transceiver can continue to carry information thatfacilitates and/or completes the handshake process between differentpairs of the multiple different receivers, thereby enabling multipledifferent pairs of transceivers to simultaneously utilize a same set oftones to carry out the handshake and/or initialization process.

FIG. 1A is a block diagram illustrating an example environment 100 inwhich two frequency division systems communicate over a same physicalcommunications medium. The environment 100 includes Frequency DivisionSystem (FDS-O) 102 and Frequency Division System (FDS-R) 104,communicating over a communication medium 120. The two frequencydivision systems communicate using multiple different transceivers thateach utilize different frequency bands to communicate. One of thetransceivers (e.g., x2TU-O 108) can be used to implement lower frequencydigital subscriber line (DSL) technologies, for example, asymmetricdigital subscriber line (ADSL) G.992.1, ADSL2plus G.992.5, very highspeed digital subscriber line (VDSL) G.993.2, or vectored VDSL G.993.5,while another transceiver (e.g., x1TU-O 106) in the frequency divisionsystem (e.g., FDS-O 102) can be used to implement higher frequencytechnologies, such as G.fast.

To establish communications channels, the FDS-O 102 and the FDS-R 104complete an initialization process to enter showtime. Showtime is astate the FDS-O 102 and the FDS-R 104 reach after the initializationprocess is completed. During showtime, the FDS-O 102 and the FDS-R 104transmit bearer channel data.

The FDS-O 102 and the FDS-O 104 respectively include bonding units 110a, b. The Bonding unit 110 a provides data to the two transceiversx1TU-O 106 and x2TU-O 108 of FDS-O 102. Likewise, the bonding unit 110 bprovides data to transceivers x1TU-R 116 and x2TU-R 118. Transceiversx1TU-O 106 and x2TU-O 108 are coupled to diplexer-O 112. The diplexer-O112 aggregates signals received from transceivers x1TU-O and x2TU-O.Furthermore, diplexer-R 112 receives and transmits data to transceiversx1TU-R 116 and x2TU-R 118 over the communication medium 120. As such,multiple different transceiver pairs utilize the same communicationmedium 120 to carry data. As discussed in more detail below, this samecommunication medium 120 is also used to initialize multiple differentcommunications channels between different pairs of transceivers.

The FDS-O 102 includes two additional transceivers x1TU-O 106 and x2TU-O108. In some implementations, the two transceivers x1TU-O 106 and x2TU-O108 operate in different frequency bands. For example, and in thisinstance, transceiver x1TU-O 106 is a low-frequency transceiver, forexample, an ADSL or VDSL transceiver. Transceiver x1TU-O 106 can have adedicated frequency band below 17.6 MHZ. In addition, tone sets usedduring the handshake process, defined in G.994.1, use low-frequencybands below 2 MHz. The tone sets are carrier frequencies thetransceivers use to execute the handshaking process.

Also in this instance, transceiver x2TU-O 108 is a high-frequencytransceiver, for example, a G.fast transceiver. Transceiver x2TU-O 108transmits data in a high-frequency band. For example, high-frequencytransceivers transmit data above 17.6 MHz. However, high-frequencytransceivers also execute the handshake process, defined in G.994.1,within a frequency band below 2 MHz.

The FDS-R 104 includes two transceivers x1TU-R 116 and x2TU-R 118. Inthis instance, transceiver x1TU-R is a low-frequency transceiver andtransceiver x2TU-R is a high-frequency transceiver. During showtime,low-frequency transceiver x1TU-O 106 transmits data to low-frequencytransceiver x1TU-R 116 using a lower frequency band. Moreover, duringshowtime high-frequency transceiver x2TU-O transmits data tohigh-frequency transceiver x2TU-R 118 using a higher frequency band.

FDS-O 102 and FDS-R 104 respectively include diplexers, diplexer-O 112and diplexer-R 114. A diplexer is a multiplexer that receives two inputsignals and combines or multiplexes these two input signals into onesignal. In some implementations, a diplexer 112,114 aggregates multipleinput signals into one output signal. In other implementations, thediplexer 112, 114 receives one input signal and separates the inputsignal into multiple output signals. In particular, the diplexerincludes a high-pass filter and a low-pass filter. In this instance, thehigh-pass filter can be configured to pass signals in frequency bandsabove 17.6 MHz to the high-frequency transceivers. Meanwhile, thelow-pass filter can be configured to pass signals in frequency bandsbelow 17.6 MHz to the low-frequency transceivers.

For example, diplexer-O 112 can receive input signals from transceiversx1TU-O 106 and x2TU-O 108 that are multiplexed into an output signal.The two input signals are each within a different frequency band e.g., alow-frequency band and a high-frequency band. The output signal can betransmitted to transceiver FDS-R 104.

FDS-R's diplexer-R 114 segregates the high-frequency signal and thelow-frequency signal using the low-pass and high-pass filters within thediplexer-R 114. The low-frequency signal is transmitted from thediplexer-R 114 to the low-frequency transceiver x1TU-R. Thehigh-frequency signal is transmitted from the diplexer-R 114 to thehigh-frequency transceiver x2TU-R 118. In some implementations, thediplexer can be replaced with a triplexer, a quadplexer, or any othersuitable multiplexer.

In this instance, the four transceivers x1TU-O 106, x2TU-O 108, x1TU-R116 and x2TU-R 118 and use two different frequency bands to transmitdata over the same communication medium 120. However, in someimplementations, the two transceivers can also use the same frequencyband to transmit data. For example, x1TU-O 106 and x2TU-O 108 can bothbe low-frequency transceivers or high-frequency transceivers. If the twotransceivers communicate using the same frequency band, the transceiverswill need to mitigate conflicting signals sent over the same frequency.For example, the two transceivers x1TU-O 106 and x2TU-O 108 can use twoseparate and uniquely dedicated communication mediums, or alternatingsending the messages between the two transceivers causing latency delaysin data transmission.

Before transceivers x1TU-O and x2TU-O enter showtime and transmit datato x1TU-R and x2TU-R respectively, the transceivers conduct aninitialization process. The initialization process includes a handshakeprocess based on G.994.1 (G.hs). The handshake process creates acommunication channel, for example, the bearer channel, between the twotransceivers. The bearer channel is the channel transmits data betweentwo transceivers during showtime.

The handshake process uses dedicated tone sets to start communicationbetween transceivers x1TU-O, x2TU-O and x1TU-R, x2TU-R respectively.However, since the high-frequency transceivers use the lower frequencyband to conduct the handshake process, while the lower frequencytransceivers use the lowers frequency band to communicate data, it isdifficult for the four transceivers to use the same communication medium120 to transmit handshake information. This is because both sets oftransceivers, i.e., the low frequency and the high frequency,simultaneously try to transmit data using the low-frequency band of thecommunication medium and a conflict of signal transmission occurs. Torectify this problem, one pair of transceivers will be used tofacilitate the handshake process for two or more different pairs oftransceivers.

For example, the low-frequency transceivers, x1TU-O 106 and x1TU-R 116,can facilitate the handshake process for the low-frequency transceiversas well as the high-frequency transceivers. In this instance,transceivers x1TU-O 106 and x1TU-R 116 conduct the handshake process forthemselves according to G.994.1, and transmit handshake information forhigh-frequency transceivers x2TU-O 108 and x2TU-R 118. In someimplementations, the high-frequency transceivers, x2TU-R, x2TU-O, cantransmit handshake information for the low-frequency transceiversaccording to description provided herein. Any transceiver pair canexecute the handshake process for one or more other transceiver pairs.

FIG. 1B is a block diagram illustrating simultaneous transmission ofhandshake information for multiple transceivers. FIG. 1B illustrates oneimplementation of example message transfers between multipletransceivers. Aspects of FIG. 3 will be described in connection withFIG. 1B. FIG. 3 is a flow chart of an example process for simultaneouslytransmitting handshaking information for multiple transceivers.

The transceivers simultaneously execute the handshake process byexpanding the G.handshake (G.hs) field in x1TU-O's G.hs message toinclude transceiver x2TU-O's handshake information, which is alsoreferred to as a set of handshake information to distinguish it from thehandshake information of x1TU-O. Handshake information includesparameters for establishing data transfer protocols between two or moretransceivers. The data transfer protocols are available modes ofoperation for a particular transceiver, which describes how theparticular transceiver can transmit data. For example, the data transferprotocols can include upstream frequency spectrums, downstream frequencyspectrums, vendor identification, which version of G.994.1 the specificequipment uses, etc.

Transceiver x1TU-O's handshake message includes the set of handshakeinformation for transceiver x2TU-O 108. Thus, transceiver x1TU-O 106simultaneously executes the handshake process for the low-frequencytransceivers, x1TU-O 106, x2TU-O 108 and the high-frequency transceiversx1TU-R 116, x2TU-R 118 using the same handshake message.

For example, and referring to FIG. 3, an initialization process of afirst transceiver is launched (310). In some implementations, theinitialization process can be launched, for example, when the firsttransceiver or FDS-O 102 is powered on or after the transceiver isreset. In this example, the particular transceiver is a low-frequencytransceiver x1TU-O 106, but the initialization process couldalternatively be launched for the high-frequency transceiver. Theinitialization process uses a given set of tones to perform theinitialization process. For example, the low-frequency transceiverx1TU-O 106 uses one of the tones according to G.994.1 (G.hs). The tonescommunicate at a frequency less than 2 MHz. Note that the specificexample tones referred to here are provided for purposes of illustrationonly and other tones defined in G.994.1 can also be used.

The process obtains a set of handshake information for a secondtransceiver that is connected to a same physical communications mediumas the first transceiver (320). In some implementations, the obtainedset of handshake information includes the handshake information that istransmitted by the second transceiver during execution of theinitialization process by the second transceiver. In this example, thesecond transceiver is transceiver x2TU-O 108, which is connected to asame physical communications medium 106 as the first transceiver, x1TU-O106. In addition, the second transceiver uses the given set of tones toperform the initialization process, for example, the G.994.1 (G.hs)tones used by x1TU-O 106.

The first transceiver can obtain the first set of handshake informationfrom the second transceiver in response to the first transceiverrequesting the first set of handshake information. For example, when theinitialization process is launched, the first transceiver can accessstored data specifying that the first transceiver is to obtain, from thesecond transceiver, information that will be embedded into the handshakemessage that will be transmitted by the first transceivers. In responseto accessing the stored data, the first transceiver can generate arequest for handshake information requesting that the second transceiverprovide its handshake information to the first transceiver, and thesecond transceiver can respond to the request for handshake informationwith the set of handshake information that is used to initialize thesecond transceiver.

In some implementations, the request for the handshake informationspecifies a time period describing an amount of time within which thesecond transceiver must transmit the set of handshake information to thefirst transceiver. In some implementations, if the first transceiverdoes not receive the handshake information within the specified timeperiod, the first transceiver sends a subsequent request to the secondtransceiver (e.g., a retry message). However, in other implementations,if the first transceiver does not receive the handshake information, thefirst transceiver continues the handshake process for the firsttransceiver without the handshake information from the secondtransceiver.

In some implementations, the first transceiver can transmit, in parallelwith the request for the set of handshake information from the secondtransceiver, a request for handshake information from a thirdtransceiver that differs from the second transceiver. Any handshakeinformation received from the third transceiver can also be embedded inthe handshake message being generated by the first transceiver, suchthat the first transceiver can simultaneously facilitate the handshakeprocess for a plurality of transceivers using the same handshakemessage. For example, the first transceiver can embed handshakeinformation for N (e.g., two or more) different transceivers into itsown handshake message to create a modified handshake message, andtransmit that modified handshake message using a same set of tones.

The first transceiver 106 inserts the set of handshake information ofthe second transceiver 108 into one or more registers (e.g., shadowregisters) of the handshake message generated by the first transceiver106. As such, the set of handshake information of the second transceiver108 is transmitted with first handshake information of the firsttransceiver 106 during initialization of the first transceiver 106(330). The registers are frames included in a message frame structureaccording to G.994.1. The handshake process is carried out by sendingmessages with the additional handshake information embedded in themessage frames of the first transceiver 106. Further details regardingthe message frame structure will be described in connection with FIG. 2.

A communications channel is initiated for the second transceiver 108over the same physical communications medium using the set of handshakeinformation that is inserted into the one or more registers (340). Insome implementations, the communications channel for the secondtransceiver 108 is initiated over the same physical medium 106 as thecommunications channel for the first transceiver 106. The communicationschannel for the second transceiver 108 is initiated, in part, by thefirst transceiver 106 transmitting the first handshake information ofthe first transceiver together with the set of handshake information forthe second transceiver using the given set of tones.

For example, referring back to FIG. 1B, transceiver x1TU-O 106 transmitsa “CLR” message to transceiver x1TU-R 116. The “CLR” message is arequest for a capabilities list for transceiver x1TU-R 116. In addition,the “CLR” message includes a capabilities list for transceiver x1TU-O106. A capabilities list specifies parameters and modes of operationthat a given transceiver can utilize. In some implementations, the modesof operation describe the transceiver's different communicationprotocols used to communicate with other transceivers. The “CLR” messagecan also include a capabilities list for transceiver x2TU-O 108, whichcan be embedded in registers of the “CLR” message transmitted bytransceiver x1TU-O 106. For example, a “CLR” message that is transmittedby low-frequency transceiver x1TU-O 106 to low-frequency transceiverx1TU-R 116 can have information from a different “CLR” message (e.g.,generated by a different transceiver) embedded in the registers of the“CLR” message transmitted by the transceiver x1TU-O 106, which isreferred to as the first “CLR” message. The different “CLR” message thatis embedded in the registers of the first “CLR” message can be generatedby and/or received from a high-frequency transceiver x2TU-O 108. Thisadditional “CLR” message can be, for example, the “CLR” message that thehigh-frequency transceiver x2TU-O 108 would have transmitted directly tohigh-frequency transceiver x2TU-R 118 using a traditional handshakeprocess. as such, the information that is embedded into the first “CLR”message can include a capabilities list for the high-frequencytransceiver x2TU-O 108, which specifies parameters and modes ofoperation for x2TU-O 108.

A controller in FDS-R 104 parses the “CLR” message and determines thatregisters of the “CLR” message received by x1TU-R includes acapabilities list for the high-frequency transceiver x2TU-R 118. Forexample, assuming that the high-frequency transceiver x2TU-O 108generated its own “CLR” message, which was then embedded in theregisters of the first “CLR” message generated by x1TU-O 106, thecontroller can extract the “CLR” message generated by high-frequencytransceiver x2TU-O 108, and transfer that extracted “CLR” message tohigh-frequency transceiver x2TU-R 118. In this example, the controllercan send instructions to low-frequency transceiver x1TU-R 116 thatinstruct x1TU-R 116 to transmit information embedded in the registers ofthe first CLR message received from x1TU-O 106 (e.g., the different“CLR” message generated by high-frequency transceiver x2TU-O 108) tohigh-frequency transceiver x2TU-R 118. In some implementations, thecontroller is separate and distinct from each transceiver x1TU-R 116 andx2TU-R 118. In other implementations, each transceiver includes aninternal controller that can parse messages and give its transceiverinstructions. In this example, transceiver x2TU-R 118 receives theinformation, and responds based on the received information. Forexample, the different “CLR” message (e.g., generated by high-frequencytransceiver x2TU-O 108) can be passed from transceiver x2TU-O 108 totransceiver x2TU-R 118, which in turn, can generates a “CL” message fortransceiver x2TU-O 108.

A “CL” message is a response message generated in response to receivinga portion or a whole “CLR” message. The “CL” message conveys a list ofpossible modes of operation for the transceiver that generates the “CL”message. In some implementations, the “CL” message specifies modes ofoperation that can be used by both of the communicating transceivers,for example, high-frequency transceivers x2TU-O 108 and x2TU-R 118. Forexample, high-frequency transceiver x2TU-R 118 can receive the “CLR”message generated by x2TU-O 108 and determine which modes of operationlisted in the “CLR” message generated by x2TU-O 108 can also be used byhigh-frequency transceiver x2TU-R 118. Based on the determination,x2TU-R 118 generates the “CL” message that specifies one or more of thepossible modes of operation that can be used by both of high-frequencytransceiver x2TU-O 108 and high-frequency transceiver x2TU-R 118.

The initiation of the communications channel for the second transceiverover the same physical communications medium, can include, the firsttransceiver x1TU-O 106 receiving a reply to the first handshakeinformation. For example, low-frequency transceiver x1TU-O 106 receivesa “CL” message from low-frequency transceiver x1TU-R 116. The reply.“CL” message includes a second set of handshake information for thesecond transceiver, e.g., the high-frequency transceiver x2TU-O 108. Thesecond set of handshake information is included in the one or moreregisters of handshake information used to initialize the firsttransceiver. In particular, similar to the discussion of the “CLR”message above, high-frequency transceiver x2TU-R's “CL” message can beembedded into registers of a different “CL” message that is generated bythe low-frequency transceiver x1TU-R 116 embeds.

The initiation of the communications channel for the second transceiverover the same physical communications medium can also includedetermining proposed communication parameters that the secondtransceiver will use to communicate with a remote transceiver over thecommunications channel established for the second transceiver. Theproposed communication parameters can be selected, for example, based onthe first set of handshake information and the second set of handshakeinformation. For example, each transceiver, the low-frequencytransceiver x1TU-O 106 and high-frequency x2TU-O 108, determinesproposed common modes of operation to communicate with their respectivelow and high-frequency transceivers x1TU-R 116. Each transceiver, thelow-frequency transceiver x1TU-O 106 and high-frequency x2TU-O 108determines the proposed common modes of operation based on the “CLR”message and the “CL” message.

The low-frequency transceiver x1TU-O 106 and high-frequency x2TU-O 108each generate an “ACK (1)+MS” message. An “ACK (1)+MS” message includestwo different components in one message. The “ACK (1)” portionacknowledges receiving a portion or a complete “CL” message. The “MS”component is a mode select message that requests the initiation of aparticular mode of operation for showtime. Again, the low-frequencytransceiver x1TU-O 1206 embeds high-frequency transceiver x2TU-O's “ACK(1)+MS” message inside of the registers of its own handshake message.

The first transceiver transmits the proposed communication parametersfor the second transceiver. For example, low-frequency transceiverx1TU-O 106 transmits an acknowledgement message that includes two “ACK(1)+MS” messages, one for low-frequency transceiver x1TU-O 106 and onefor high-frequency transceiver x2TU-O 108.

Low-frequency transceiver x1TU-R 116 and high-frequency transceiverx2TU-R 118 individually receive their respective “ACK (1)+MS” messages.For example, the “ACK(1)+MS” message for the high-frequency transceiverx2TU-R 118 can be extracted from the acknowledgement message that isreceived by the low-frequency transceiver x1TU-R 116, and provided tothe high-frequency transceiver x2TU-R 118 (e.g., by a controller).Low-frequency transceiver x1TU-R 116 and high-frequency transceiverx2TU-R 118 each generate respective “ACK (1)” messages. In thisinstance, the “ACK(1)” message acknowledges receiving a partial orcomplete “MS” message and initiates the G.994.1 clear-down procedure.High-frequency transceiver x2TU-R's “ACK (1)” message is embedded intothe registers of low-frequency transceiver x1TU-R's “ACK” 1 message.Low-frequency transceiver x1TU-R transmits the “ACK (1)” message forboth transceivers to low-frequency transceiver x1TU-O 106 in a samemessage.

The first transceiver receives an acceptance of the proposedcommunication parameters. For example, the low-frequency transceiverx1TU-O 106 receives the “ACK (1)” message from low-frequency transceiverx1TU-R 116. The low-frequency transceiver x1TU-O 106 transmits the “ACK(1)” message from high-frequency transceiver x2TU-R 118 tohigh-frequency transceiver x2TU-O 108.

The low-frequency transceiver x1TU-O 106 initiates low-frequencycommunication 152 with low-frequency transceiver x1TU-R 1106 using thecommunication medium 120. Likewise, independent communication isinitiated between the second transceiver and a respective transceiverwithin the remote transceiver. For example, the high-frequencytransceiver x2TU-O 108 initiates high-frequency communication 154 withhigh-frequency transceiver x2TU-R 118 using the same communicationmedium 120 as the low-frequency communication 152.

FIG. 2 is a block diagram depicting a handshake (G.hs) message frame 202structure. This corresponds to a high-level data control (HDLC) frame202 structure, wherein each frame begins and ends with a standard HDLCflag octet (“01111110”). Each G.hs message makes up one or more frames202. Low-frequency transceivers x1TU-O 106, x1TU-R 116 embed handshakeinformation for high-frequency transceivers x2TU-O 108, x2TU-R 118 inempty registers or frames 202 of the G.hs message. For example, alow-frequency transceiver x1TU-O 106, x1TU-R 116 may add additionalframes 202 to the G.hs message to include the G.hs message of thehigh-frequency transceiver x2TU-O 108, x2TU-R 118.

In order to identify the messages that are directed to thehigh-frequency transceivers, a unique MAC address or an IDS (identitysequence) may be used in the G.994.1 identification field that arededicated to the individual transceivers (e.g., for the initializationprocess).

As an example, a message frame may include a destination MAC address(MAC address of the G.994.1 process of the destination high-frequencytransceiver), a source MAC address (MAC address of the G.994.1 processof the source high-frequency transceiver), a length field (as per theIEEE 802.3 MAC frame format), a logic link control header coding for thesubnetwork access protocol (3 bytes, AA-AA-03), a subnetwork accessprotocol data unit header containing a 3-octet organization code and a2-octet Protocol ID for a private protocol, a Protocol Payload Data(G.994.1 HDLC frame including Flags, Message segment, frame checksequence (FCS)), and a standard Ethernet 4-byte FCS (as per the IEEE802.3 Ethernet frame FCS).

The high-frequency transceivers x2TU-O 108, x2TU-R 118 may then exchangeG.hs messages using the message frames described above. The G.hsprotocol may remain unchanged including messages transmitted during thehandshake process.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments of particular inventions.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults.

What is claimed is:
 1. A method, comprising: launching an initializationprocess of a first transceiver, wherein the initialization process usesa given set of tones to perform the initialization process; obtaining,for a second transceiver that is connected to a same physicalcommunications medium as the first transceiver and uses the given set oftones to perform the initialization process, a set of handshakeinformation transferred by the second transceiver during theinitialization process; inserting the set of handshake information ofthe second transceiver into one or more registers that are transmittedwith first handshake information of the first transceiver duringinitialization of the first transceiver; and initiating a communicationschannel for the second transceiver over the same physical communicationsmedium using the set of handshake information that was inserted into theone or more registers, including transmitting, by the first transceiver,the first handshake information of the first transceiver together withthe set of handshake information for the second transceiver over thesame physical communications medium using the given set of tones.
 2. Themethod of claim 1, wherein initiating a communications channel for thesecond transceiver over the same physical communications medium,comprises: receiving, by the first transceiver, a reply to the firsthandshake information that includes a different set of handshakeinformation for the second transceiver, wherein the different set ofhandshake information is included in the one or more registers that aretransmitted with the first handshake information used to initialize thefirst transceiver; determining, based on the set of handshakeinformation and the different set of handshake information, proposedcommunication parameters that the second transceiver will use tocommunicate with a remote transceiver over the communications channelestablished for the second transceiver; and transmitting, from the firsttransceiver, the proposed communication parameters for the secondtransceiver.
 3. The method of claim 2, further comprising: receiving, bythe first transceiver, an acceptance of the proposed communicationparameters; and initiating independent communication between the secondtransceiver and a respective transceiver within the remote transceiver.4. The method of claim 1, wherein obtaining a set of handshakeinformation transferred during the initialization process, comprisesrequesting, by the first transceiver and from the second transceiver,the set of handshake information of the second transceiver, wherein therequest includes a time period specifying an amount of time for thesecond transceiver to transmit the set of handshake information.
 5. Themethod of claim 4, further comprising requesting, in parallel with therequest from the second transceiver and from a third transceiver, asecond different set of handshake information of the third transceiver.6. The method of claim 1, wherein handshake information comprisesparameters for establishing data transfer protocols between two or moretransceivers.
 7. A communications transceiver, comprising: a diplexer; afirst transceiver connected to the diplexer, wherein the firsttransceiver users a given set of tones to perform an initializationprocess; and a second transceiver connected to the diplexer, wherein thesecond transceiver also uses the given set of tones to perform theinitialization process, the second transceiver and the first transceiverboth communicate over a same physical communications medium, and thesecond transceiver performs operations comprising: launching aninitialization process, wherein the initialization process uses thegiven set of tones to perform the initialization process; obtaining,from the first transceiver, a set of handshake information transferredby the first transceiver during the initialization process; insertingthe set of handshake information of the first transceiver into one ormore registers that are transmitted with second handshake information ofthe second transceiver during initialization of the second transceiver;and initiating a communications channel for the first transceiver overthe same physical communications medium that is connected to thediplexer using the set of handshake information that was inserted intothe one or more registers, including transmitting the second handshakeinformation of the second transceiver together with the set of handshakeinformation for the first transceiver over the same physicalcommunications medium using the diplexer and using the given set oftones.
 8. The system of claim 7, wherein initiating a communicationschannel for the first transceiver over the same physical communicationsmedium, comprises: receiving a reply to the second handshake informationthat includes a different set of handshake information for the firsttransceiver, wherein the different set of handshake information isincluded in the one or more registers that are transmitted with thesecond handshake information used to initialize the second transceiver;determining, based on the set of handshake information and the differentset of handshake information, proposed communication parameters that thefirst transceiver will use to communicate with a remote transceiver overthe communications channel established for the first transceiver; andtransmitting, from the second transceiver, the proposed communicationparameters for the first transceiver.
 9. The system of claim 8, whereinthe instructions cause the second transceiver to: receiving anacceptance of the proposed communication parameters; and initiatingindependent communication between the first transceiver and a respectivetransceiver within the remote transceiver.
 10. The system of claim 7,wherein obtaining a set of handshake information transferred during theinitialization process, comprises requesting from the first transceiver,the set of handshake information of the first transceiver, wherein therequest includes a time period specifying an amount of time for thefirst transceiver to transmit the set of handshake information.
 11. Thesystem of claim 10, wherein the instructions cause the secondtransceiver to perform operations further comprising requesting, inparallel with the request from the first transceiver and from a thirdtransceiver, a second different set of handshake information of thethird transceiver.
 12. The system of claim 7, wherein handshakeinformation comprises parameters for establishing data transferprotocols between two or more transceivers.
 13. A non-transitorycomputer storage medium storing instructions that when executed by oneor more data processing apparatus cause the one or more data processingapparatus to perform operations comprising: launching an initializationprocess of a first transceiver, wherein the initialization process usesa given set of tones to perform the initialization process; obtaining,for a second transceiver that is connected to a same physicalcommunications medium as the first transceiver and uses the given set oftones to perform the initialization process, a set of handshakeinformation transferred by the second transceiver during theinitialization process; inserting the set of handshake information ofthe second transceiver into one or more registers that are transmittedwith first handshake information of the first transceiver duringinitialization of the first transceiver; and initiating a communicationschannel for the second transceiver over the same physical communicationsmedium using the set of handshake information that was inserted into theone or more registers, including transmitting the first handshakeinformation of the first transceiver together with the set of handshakeinformation for the second transceiver over the same physicalcommunications medium using the given set of tones.
 14. Thenon-transitory computer storage medium of claim 13, wherein initiating acommunications channel for the second transceiver over the same physicalcommunications medium, comprises: receiving a reply to the firsthandshake information that includes a different set of handshakeinformation for the second transceiver, wherein the different set ofhandshake information is included in the one or more registers that aretransmitted with the first handshake information used to initialize thefirst transceiver; determining, based on the set of handshakeinformation and the different set of handshake information, proposedcommunication parameters that the second transceiver will use tocommunicate with a remote transceiver over the communications channelestablished for the second transceiver; and transmitting the proposedcommunication parameters for the second transceiver.
 15. Thenon-transitory computer storage medium of claim 14, wherein theinstructions cause the one or more data processing apparatus to performoperations further comprising: receiving an acceptance of the proposedcommunication parameters; and initiating independent communicationbetween the second transceiver and a respective transceiver within theremote transceiver.
 16. The non-transitory computer storage medium ofclaim 13, wherein obtaining a set of handshake information transferredduring the initialization process, comprises requesting, from the secondtransceiver, the set of handshake information of the second transceiver,wherein the request includes a time period specifying an amount of timefor the second transceiver to transmit the set of handshake information.17. The non-transitory computer storage medium of claim 16, wherein theinstructions cause the one or more data processing apparatus to performoperations further comprising requesting, in parallel with the requestfrom the second transceiver and from a third transceiver, a seconddifferent set of handshake information of the third transceiver.
 18. Thenon-transitory computer storage medium of claim 13, wherein handshakeinformation comprises parameters for establishing data transferprotocols between two or more transceivers.